CA2143092C - Process for the production of fine denier cellulose acetate fibers - Google Patents
Process for the production of fine denier cellulose acetate fibersInfo
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- CA2143092C CA2143092C CA002143092A CA2143092A CA2143092C CA 2143092 C CA2143092 C CA 2143092C CA 002143092 A CA002143092 A CA 002143092A CA 2143092 A CA2143092 A CA 2143092A CA 2143092 C CA2143092 C CA 2143092C
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- cellulose acetate
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof
- D01F2/24—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from cellulose derivatives
- D01F2/28—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from cellulose derivatives from organic cellulose esters or ethers, e.g. cellulose acetate
- D01F2/30—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof from cellulose derivatives from organic cellulose esters or ethers, e.g. cellulose acetate by the dry spinning process
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- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Artificial Filaments (AREA)
- Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)
Abstract
A method for producing ultra-fine denier cellulose acetate fibers that entails spinning a spinning solution containing adequately high amounts of cellulose acetate in acetone wherein the cellulose acetate has a falling ball viscosity of 15 to 70 seconds wherein the spinning is conducted through spinnerettes having holes that have a diameter of less than 36 microns followed by drying at a temperature of 50 to 80.degree. C at a draw ratio of 0.9 to 1.7.
Description
PROCESS FOR THE PRODUCTION O
FINE DENIER CELLULOSE ACETATE FIBERS
Field of the Invention The present invention relates to a process for the production of fine denier cellulose acetate fibers. The present invention more specifically entails the process for producing ultra-fine denier cellulose acetate fibers having an average denier per filament of less than 1.4 (0.16 TEX).
Background of the Invention Cellulose acetate fibers have been used for many years to produce many products such as textile yarns, for making fabrics, and filter tow that is used in the production of filter rods for use in tobacco smoke filters. Cellulose acetate fibers are generally produced by a dry spinning process such as those disclosed in U.S. 2,829,027, U.S. 2,838,364, and U.S.
3,080,611. The cellulose acetate fibers are generally dry spun from a cellulose acetate spinning solution containing cellulose acetate and acetone with other optional additives such as titanium dioxide. The dry spinning process of producing the cellulose acetate fibers generally produces fibers having an average denier per filament of 2 to 8 (0.22 to 0.89 TEX).
Fine denier filaments of cellulose acetate are more preferred for the manufacture of soft and smooth specialty fabrics. Additionally, when used in tobacco smoke filters, cellulose acetate fibers at the lower range of average denier per filament have a greater surface area exposed to the smoke passing through the filter and thus filtration efficiency is increased.
In light of the desirable results obtained from the fine denier cellulose acetate fibers, attempts have been made to commercially manufacture reduced denier per filament fibers. Previous attempts to redur.e the average denier per filament of cellulose acetate fibers included reducing the viscosity of the spinning solution or spinning dope by reducing the solids content as disclosed in U.S. 3,033,698. However, spinning of this low viscosity spinning solution tends to cause the extruded fibers to stick to the metal surface of the spinnerettes and thus it is difficult to pull these fibers into a yarn. Methods of producing lower average denier per filament fibers by lowering the solids content also present flow rate control problems and increase the amount of acetone that needs to be recovered. Another method of reducing the average denier per filament of cellulose acetate fibers entails the modification of the holes in the spinnerettes in addition to lower solids content as disclosed in U.S. 3,608,041.
Other methods of producing fine denier cellulose acetate fibers that also entail reducing the viscosity of the solution by reducing solids, correct the stickiness problems by adding metal chelates to the spinning solution such as disclosed in U.S. 3,033,698, U.S. 3,038,780, and U.S. 3,068,063. However, acetone recovery is still a problem and the long term toxicity of these metal chelates is not known, thus these products are not acceptable for tobacco smoke filters.
Also end users are reluctant to use fibers with unusual additives.
Another method of reducing the average denier per filament of the fiber entails increasing the draw ratio, however, when producing fine denier fibers by simply increasing the draw ratio, breakage of the filaments is unacceptably high.
It would be very desirable to be able to produce ultra-fine denier filaments using a spinning solution of normal to high solids content without dramatically changing spinning conditions or the addition of unusual additives.
Summa ~ of the Invention The process of the present invention entails the production of ultra-fine denier cellulose acetate fibers according to the process that comprises:
(A) forming a spinning solution containing 24 up to 32 weight percent cellulose acetate, 0 up to a minor amount of Ti02, a minor amount of water, with the remainder being acetone, wherein said cellulose acetate has a falling ball viscosity of to 70 seconds;
(B) spinning said spinning solution at an elevated temperature through spinnerettes having a multiplicity of holes having a diameter less than 36 ~m to form a fiber;
~ drying said fibers in a gaseous media that is at a temperature of 50 to 80~ C wherein said fibers are spun at a draw ratio of 0.9 to 1.7 thereby producing fibers having an average denier per filament of less than 1.4 (0.16 TEX).
Detailed Description of the Invention The applicants have unexpectedly discovered an improved process for producing ultra-fine denier fibers that have an average denier per filament of less than 1.4 (0.16 TEX) that does not require the addition of unusual additives, reduced solids, or dramatic changes in spinning conditions. This process of producing ultra fine denier fibers is possible due to the normal to high solids content spinning solution containing a cellulose acetate that has a falling ball viscosity of 15 to 70 seconds that is spun through spinnerettes having a diameter less than 36 ,um at the defined drying or curing conditions.
In the process of the present invention for producing the ultra-fine denier cellulose acetate fibers, a spinning solution is formed containing 24 to 32 weight percent cellulose acetate, 0 up to a minor amount of Ti02, a minor amount of water with the remainder being acetone wherein the cellulose acetate has a falling ball viscosity of 15 to 70 seconds.
This spinning solution is preferably formed at room temperature up to the boiling point of the solution, more preferably between 30 and 50C. Mixing the spinning solution at temperatures much below room temperature does not adequately permit the formation of a homogenous mixture of acetone and cellulose acetate whereas temperatures above the boiling point of acetone in the solution are clearly undesirable.
The solids content of the spinning solution is generally between 24 and 32 weight percent cellulose acetate with zero to very minor amounts of titanium dioxide. The cellulose acetate content is preferably above 25 up to 32 weight percent, more preferably about 26 to 30 weight percent. At the higher solids content, there is less acetone present in the spinning solution, thus the need for acetone recovery is reduced. However, at a solids content much above 32 weight percent, the spinning solution is too viscous to be extruded through the small spinnerette holes.
Whereas, at a solids content much below 25 weight percent, the flow rate of the dope through the spinnerette is difficult to control and the amount of acetone to recover is too high. Additionally, spinning solutions containing low solids when spun into fibers tend to cause the fibers to stick to the outside surface of the metal face of the spinnerettes and are, therefore, difficult to pull the filaments into a yarn.
The cellulose acetate used in the spinning solution has a falling ball viscosity that is preferably below 42 seconds, more preferably below 35 seconds. Falling ball viscosity is defined as the time in seconds for a stainless steel ball ~f 1/8 inch in diameter (3.17 mm) to pass between two sets of parallel and horizontal lines separated by 2.25 inches (5.71 cm) through a solution of 20 weight percent cellulose acetate and 80 weight percent acetone at 25C. Falling ball viscosity is generally reduced by lowering the average molecular weight of cellulose acetate. The molecular weight of cellulose acetate may be adjusted by proper selection of esterification conditions by those skilled in the art. The falling ball viscosity for this cellulose acetate is the preferred range of 20 to 42 seconds with a range of 25 to 40 seconds being more preferred. Cellulose acetates of falling ball viscosities higher than 42 seconds are less desirable since the resulting spinning solution becomes too viscous to ad?quately extrude through the fine diameter holes in the spinnerettes. However, a cellulose acetate that has a falling ball viscosity much below 15 seconds, when formed into a spinning solution, results in a spinning solution of too low a viscosity to permit fiber formation out of the end of the holes in the spinnerettes. The inherent viscosity of the cellulose acetate in the spinning solution is preferably 1.35 to 1.60 more preferably 1.45 to 1.58 with a cellulose acetate inherent viscosity below 1.56 being most preferred.
The spinning solution according to the present invention generally has minor amounts of titanium dioxide added and minor amounts of water. The amount of Ti02 in the total spinning solution is generally below one weight percent, more preferably below 0.5 weight percent, with a weight percent of Ti02 less than 0.3 weight percent being most preferred. A minor amount of Ti02 is added to increase the whiteness of the resulting filter tow whereas higher amounts of Ti02 tend to plug the fine spinnerette holes.
The amount of water present in the spinning solution of the present invention is generally less than 3 weight percent, more preferably between 1 and 2 weight percent. Amounts of water much above 3 weight percent tend to slow the drying time of the resulting fibers whereas amounts of water much below 1 weight percent are difficult to obtain since the acetone is recycled from water by distillation and ambient air is humid.
The spinning solution is spun according to the present invention at an elevated temperature through the holes in the spinnerettes that have a diameter of less than 36 ~m to form a fiber. The spinning temperature of the spinning solution in the process of the present invention is preferably as hot as possible but below the boiling point of acetone. The elevated temperature of the spinning solution is maintained by passing through a heated candlefilter. The candlefilter temperature is maintained by passing hot water through the internal channels of the candlefilter. The actual temperature of the spinning solution is a few degrees below the candlefilter water temperature. This hot water temperature is preferably between 40 and 65C with a temperature of 50 to 60C
being more preferred. Candlefilter water temperatures much above 65C can heat the spinning solution above the boiling point of the acetone and tend to cause the formation of bubbles on the surface of the extruded fibers. However, candlefilter water temperatures much below 40C causes the viscosity of the spinning solution to be too high and also lengthens the curing or drying time of the spun fiber.
The holes in the spinnerettes used in the process of the present invention can be of any shape.
However, these holes are preferably round due to the ease in manufacturing of round holes in spinnerettes.
Additionally fibers produced by extrusion through non-round holes tend to have an increased pressure drop when used in a tobacco smoke filter. This increased pressure drop is such that the same unit pressure drop for a fiber from a round spinnerette hole produces higher filtration efficiency than that of the fibers from a non-round spinnerette hole cross section, such as a Y cross section.
The diameter of the holes in the spinnerettes used in the process of the present invention are preferably between 20 and 36 Vim. In general, smaller hole sizes are required to spin fibers having lower average denier per filament. When producing cellulose acetate fibers having an average denier per filament of 1.2 (0.13 TEX), the diameter of the holes in the spinnerettes is more preferably 28 to 34 ~m with a diameter of 30 to 32 ~m being most preferred.
The spinnerettes of the present invention preferably have a round hole profile such that the conical section in the back of the hole gradually tapers to form a cylindrical hole at the exit of the spinnerette. The round hole profiles are more preferably selected from hyperbola and multi-angle hole profiles. The surfaces of the spinnerette holes are preferably extremely smooth. These spinnerette holes more preferably have a surface roughness less than 0.05 Ra Vim. Ra indicates the arithmetic roughness average of the surface.
g _ The spinnerettes of the present invention are preferably of improved quality compared to the quality of spinnerettes acceptable for producing fibers of cellulose acetate having filament size in the range of 2 to 8 denier per filament (0.22 to 0.89 TES). This improved quality is especially manifest in the uniform and symmetrical shape of holes having extremely smooth surface finish. The holes at the exit of the spinnerette have cylindrical shape of 30 ~m in diameter and lengths which may be selected within the range of 0.5 to 1.5 times the diameter of the hole.
The improved quality spinnerette holes preferably have cylindrical sections with a surface roughness of 0.005 to 0.025 Ra Vim. The upstream portion of the spinnerette holes is commonly known as the countersink and has a profile which gradually increases for the diameter of the cylindrical hole section by gradually increasing the angle that the wall of the countersink makes with the axis of the hole. This may be accomplished by having a continuously increasing angle of the countersink wall with a profile such as that of a parabola. Alternatively, the countersink may be comprised of multiple frustoconical sections in which the apex angles of the sections increase as the diameter of frustoconical profile increases. For example, for two frustoconical sections, the smallest frustoconical section adjacent to and immediately upstream from the cylindrical section may have an apex angle in the range of 10 to 30 degrees and the length 34 of said section may be 3 to 10 times the diameter of the cylindrical section of the spinnerette hole. For the frustoconical section next farther upstream, the apex angle of said section may be in the range of 40 to 70 degrees and the length may be greater than 10 times the diameter of the cylindrical section of the spinnerette hole. The frustoconical sections of improved quality spinnerette holes preferably have a surface roughness within the range of 0.025 to 0.050 Ra Vim. The exterior surface or face of the improved quality spinnerette preferably has a surface roughness $ Of 0.005 t0 0.025 Ra ~,l.m.
By contrast, spinnerettes that are acceptable for producing cellulose acetate fibers having a denier per filament in the range of 2 to 8 (0.22 to 0.89 TEX) when a single countersink of frustoconical section can have a apex angle of 40 to 70 degrees. The smoothness of the finish of surfaces of the cylindrical holes, the frustoconical section and the exterior face of these spinnerettes is not as important as that of spinnerettes employed for producing fiber having less than 1 . 4 denier per f filament ( 0 . 16 TEX) .
The fiber that is spun through the spinnerette holes is dried or cured in a gaseous media at a temperature of 50 to 80C. This drying is preferably conducted in a drying cabinet with a lower top air temperature and a higher bottom air temperature of 60 to 110C. These temperatures are more preferably 60 to 70C for the top and 70 to l00C for the bottom with a bottom cabinet temperature of 80 to 90C being most preferred.
The spun fibers, prior to complete curing or drying, are spun at a draw ratio (winding speed/extrusion speed) of 0.9 to 1.7, more preferably 1 to 1.6 with a draw ratio of 1.2 to 1.5 being most preferred. At draw ratios much below 0.9 the fibers tend to flutter together and stick since the shrinking fiber does not make up for the reduced take up speed.
V~Ihereas draw ratios much above 1.7 cause fiber breakage due to the significant stretching of fibers.
It is preferred that the draw ratio generally be higher than 1 to help lower the denier, thus a draw ratio of 1.2 to 1.5 is most preferred.
The ultra-fine denier cellulose acetate fibers provided according to the present invention generally have an average denier per filament of less than 1.4 (0.16 TEX) more preferably less than 1.2 (0.13 TEX).
The fibers produced according to the present invention generally have an average denier per filament range of 0.6 to 1.4 (0.07 to 0.16 TEX) more preferably 1.0 to 1.4 (0.11 to 0.16 TEX) with an average denier per filament of 1.0 to 1.2 (0.l1 to 0.l3 TEX) being most preferred. Average denier per filaments of greater than 1.4 (0.16 TEX) do not adequately increase the filtration efficiency of filter products to be of great benefit. Whereas, an average denier per filament much below 1.0 (0.11 TEX) does not significantly increase filtration efficiency to match the increased pressure drop across a filter.
The following examples are to illustrate the present invention but should not be intended to limit the reasonable scope thereof.
EXAMPLES
EXAMPLE I
A spinning solution was formed by mixing at a temperature of 35~C 26.4 wt. percent cellulose acetate, 0.133 wt. percent titanium dioxide, less than 2 wt. percent water and the remainder being the solvent, acetone. The cellulose acetate had a falling ball viscosity of 40 seconds and an acetyl content of 39.5 wt. percent. This spinning solution was filtered and was spun through 30 and 32 ~.m round-hole dry spinnerettes from Nippon Nozzle Ltd., there being 450 holes in each spinnerette, and the holes being of improved surface finish with multiple-conical taper leading to the final cylindrical holes as described above. A total denier of 515 and 520 (57 and 58 TEX) were obtained at the speed of 466 m/m and 453 m/m, respectively. The spinning draws were 1.54 and 1.35 and denier per filaments were 1.14 and l.16 (0.13 and 0.13 TEX) for these respective runs. The candlefilter water temperature was set at 55~C, top air temperature was set at 75~C, and bottom air temperature was set at 90~C for both spinning runs. Spinning performance was satisfactory and yarn quality was satisfactory at these speeds. At these spinning conditions, a few yarn packages were successfully spun. The spinning performance of the 32 ~.m diameter hole spinnerette was better than that of the 30 ~m diameter hole spinnerette.
EXAMPLE II
A spinning solution was formed as described in Example I. This spinning solution was filtered and spun through a spinnerette having 450 round holes of 32m diameter and improved hole quality as described in Example I. The 450-filament strand had a total denier of 532 (59 TEX), an average of 1.20 denier per filament (0.13 TEX) and a calculated spin draw of 1.52. The spinning speed was 525 m/m, and other spinning conditions were like those described in Example I. One hundred and sixteen package strands of fiber were wound. Filter tows were made by combining 56 package strands to make a crimped tow of 30,000 total denier. These tows were processed into filter rods on a miniature/PM-2 plugmaker machine. Pressure drop generation of filter rods was measured on a Filtrona APD 2-V machine. Filters with 23.95 mm circumferences and 3l.5 mm length were cut from the rods, and they were attached to commercial cigarette tobacco columns. These cigarettes with 1.2 denier per filament (0.13 TEX) tow filters were tested for filtration efficiency by the FTC method. These results are shown in Table 1.
Table 1 Tow Item Rod Dimension Rod P.D. Rod Wt, 1.2/30,000/Reg. 24.45mm Cir. x 126mm L. 490mm 58omg 1.2/30,000/Reg. 24.45mm Cir. x 126mm L. 685mm 660mg 3.0/35,000/Y 24.45mm Cir. x 126mm L. 280mm*
ssomg 3.0/35,000/Y 24.45mm Cir. x 126mm L. 3'.'9mm*
660mg Filter Dimension Filter P.D. Tar Fil. Eff.
1$ 24.45mm x31.5mm L. 122.5mm 65.80 24.45mm x31.5mm L. 171.5mm 74.5%
24.45mm x31.5mm L. 122.5mm 58.0%
24.45mm x31.5mm L. 171.5mm 64.4%
* Theoretical values based on mathematical models.
As shown in this example, the pressure drop generation and filtration efficiencies of 1.2 denier (0.13 TEX) regular round cross section filter tow are significantly higher than 3.0 denier (0.33 TEX) Y cross section filter tow which is more commonly used in cigarette filters.
EXAMPLE III
A portion of the spinning solution prepared in Example II was used to spin fiber through spinnerettes having round holes of 32 ~m diameter and having normal surface finish and the single-conical taper leading to the final cylindrical holes at the exits of the spinnerette face. Fiber was able to be produced, however the frequency of breaks indicate that satisfactory commercial spinning could not be achieved at any of several spinning conditions of winding speed in the range of 400 to 600 m/m and of candle-filter water temperatures in the range of 50 to 65~C.
EXAMPLE IV
A spinning solution was formed by mixing at a temperature of 35~C 27.1 wt. percent cellulose acetate, 0.133 wt. percent titanium dioxide, less than 2 wt. percent water the remainder being the solvent, acetone. The cellulose acetate had a falling ball viscosity of 37 seconds and an acetyl content of 39.5 wt. percent. This spinning solution was filtered and was spun through a 32 ~,m round-hole spinnerette, there being 450 holes in the spinnerette and the holes being of improved surface finish with multiple-conical taper leading to the final cylindrical holes as described in Example I. A total denier of 539 was obtained at the speed of 710 m/m. The calculated spinning draw was 1.56 and the average denier per filament was 1.20 (0.13 TEX). The candle-filter water temperature was set at 60~C, the top air temperature was set at 70~C, and the bottom air temperature was set at 90~C. Even with this relatively high level of cellulose acetate concentration in the spinning solution and relatively high spinning speed, the spinning performance was satisfactory and 90 packages of fiber with each having 3.4 pounds of fiber were spun. A
bundle of 56 package strands were crimped into a tow on a crimper. Satisfactory crimped tows were made and these tows were processed into filter rods on a miniature/PM-2 plugmaker without any difficulty. Pressure drop of filter rods was measured on a Filtrona APD 2-V machine, and filtration efficiencies of 15 mm filters were measured by the FTC method. Cigarettes were smoked on the smoking machine up to 23 mm from the mouth end of the cigarette to measure the filtration efficiencies. The pressure drop measurement and filtration efficiencies results are shown in Table 2.
Table 2 Tow Item Rod Dimension Rod P.D. Rod Wt.
1.2/30,000/Reg. 23.95mm Cir. x 120mm L. 622mm 640mg 1.2/30,000/Reg. 23.95mm Cir. x 120mm L. 800mm 877mg 3.0/35,000/Y 23.95mm Cir. x 120mm L. 423mm 640mg 3.0/35,000/Y 23.95mm Cir. x 120mm L. - 877mg**
Filter Dimension Filter P.D. Tar Fil. Eff.
23.95mm xl5mm L. 78mm 45.2g 23.95mm xl5mm L. 114mm 52.5%
23.95mm xl5mm L. 78mm 42.0%
23.95mm xl5mm L. 114mm 45.9g*
* Theoretical values based on mathematical models.
** Not achievable weight for the size of rod.
As shown in Table 2, significant increases of pressure drop generation and filtration efficiencies were observed when compared with a conventional filter material.
EXAMPLE V
A spinning trial was performed to optimize the spinning condition for making ultra-fine denier filaments. A
fractional factorial experiment was performed with 6 spinning variables such as denier per filament, candlefilter water temperature, cabinet top air temperature and flow rate, and cabinet bottom air temperature and flow rate. In this experiment, a regular spinning solution which had 26.4 weight percent cellulose acetate, 0.113 weight percent Ti02, less than 2 wt. percent water and the remainder being the solvent, acetone, was used. At each spinning condition, maximum spinning speed was measured by increasing the godet roll speed gradually until the bundle of filaments started to generate broken filament. The maximum spinning speeds obtained were fitted to a regression model as follows:
Maximum Spinning Speed = 476.2 + 102.9 x DPF - 14.9 x Top Air Temp.
+ 2.1 x Candlefilter Temp.
- 5.4 x Top Air Temp. x Candlefilter Temp.
The coefficient of correlation (R2) was 0.995. This regression model showed that the lower denier per filament is more difficult to spin, and low top air temperature is preferred to spinning low denier per filament cellulose acetate fiber.
The spinning trials in the examples proved that ultra-fine denier acetate fiber can be spun without reducing the solids level of the spinning solution. For spinning ultra-fine denier fiber, it is essential to reduce the cellulose acetate I.V, or falling ball viscosity low enough to make a spinning solution with a viscosity below the level obtained by reduced solids spinning solution. Our spinning trials were confined to 1.2 denier per filament fiber (0.13 TEX), but it is possible to spin lower than 1.2 denier without changing the dope solids, if the acetate I.V. is lowered below 1.56 but not lower than l.35. An acetate I.V. lower than 1.35 would make yarn tensile property unacceptably low.
FINE DENIER CELLULOSE ACETATE FIBERS
Field of the Invention The present invention relates to a process for the production of fine denier cellulose acetate fibers. The present invention more specifically entails the process for producing ultra-fine denier cellulose acetate fibers having an average denier per filament of less than 1.4 (0.16 TEX).
Background of the Invention Cellulose acetate fibers have been used for many years to produce many products such as textile yarns, for making fabrics, and filter tow that is used in the production of filter rods for use in tobacco smoke filters. Cellulose acetate fibers are generally produced by a dry spinning process such as those disclosed in U.S. 2,829,027, U.S. 2,838,364, and U.S.
3,080,611. The cellulose acetate fibers are generally dry spun from a cellulose acetate spinning solution containing cellulose acetate and acetone with other optional additives such as titanium dioxide. The dry spinning process of producing the cellulose acetate fibers generally produces fibers having an average denier per filament of 2 to 8 (0.22 to 0.89 TEX).
Fine denier filaments of cellulose acetate are more preferred for the manufacture of soft and smooth specialty fabrics. Additionally, when used in tobacco smoke filters, cellulose acetate fibers at the lower range of average denier per filament have a greater surface area exposed to the smoke passing through the filter and thus filtration efficiency is increased.
In light of the desirable results obtained from the fine denier cellulose acetate fibers, attempts have been made to commercially manufacture reduced denier per filament fibers. Previous attempts to redur.e the average denier per filament of cellulose acetate fibers included reducing the viscosity of the spinning solution or spinning dope by reducing the solids content as disclosed in U.S. 3,033,698. However, spinning of this low viscosity spinning solution tends to cause the extruded fibers to stick to the metal surface of the spinnerettes and thus it is difficult to pull these fibers into a yarn. Methods of producing lower average denier per filament fibers by lowering the solids content also present flow rate control problems and increase the amount of acetone that needs to be recovered. Another method of reducing the average denier per filament of cellulose acetate fibers entails the modification of the holes in the spinnerettes in addition to lower solids content as disclosed in U.S. 3,608,041.
Other methods of producing fine denier cellulose acetate fibers that also entail reducing the viscosity of the solution by reducing solids, correct the stickiness problems by adding metal chelates to the spinning solution such as disclosed in U.S. 3,033,698, U.S. 3,038,780, and U.S. 3,068,063. However, acetone recovery is still a problem and the long term toxicity of these metal chelates is not known, thus these products are not acceptable for tobacco smoke filters.
Also end users are reluctant to use fibers with unusual additives.
Another method of reducing the average denier per filament of the fiber entails increasing the draw ratio, however, when producing fine denier fibers by simply increasing the draw ratio, breakage of the filaments is unacceptably high.
It would be very desirable to be able to produce ultra-fine denier filaments using a spinning solution of normal to high solids content without dramatically changing spinning conditions or the addition of unusual additives.
Summa ~ of the Invention The process of the present invention entails the production of ultra-fine denier cellulose acetate fibers according to the process that comprises:
(A) forming a spinning solution containing 24 up to 32 weight percent cellulose acetate, 0 up to a minor amount of Ti02, a minor amount of water, with the remainder being acetone, wherein said cellulose acetate has a falling ball viscosity of to 70 seconds;
(B) spinning said spinning solution at an elevated temperature through spinnerettes having a multiplicity of holes having a diameter less than 36 ~m to form a fiber;
~ drying said fibers in a gaseous media that is at a temperature of 50 to 80~ C wherein said fibers are spun at a draw ratio of 0.9 to 1.7 thereby producing fibers having an average denier per filament of less than 1.4 (0.16 TEX).
Detailed Description of the Invention The applicants have unexpectedly discovered an improved process for producing ultra-fine denier fibers that have an average denier per filament of less than 1.4 (0.16 TEX) that does not require the addition of unusual additives, reduced solids, or dramatic changes in spinning conditions. This process of producing ultra fine denier fibers is possible due to the normal to high solids content spinning solution containing a cellulose acetate that has a falling ball viscosity of 15 to 70 seconds that is spun through spinnerettes having a diameter less than 36 ,um at the defined drying or curing conditions.
In the process of the present invention for producing the ultra-fine denier cellulose acetate fibers, a spinning solution is formed containing 24 to 32 weight percent cellulose acetate, 0 up to a minor amount of Ti02, a minor amount of water with the remainder being acetone wherein the cellulose acetate has a falling ball viscosity of 15 to 70 seconds.
This spinning solution is preferably formed at room temperature up to the boiling point of the solution, more preferably between 30 and 50C. Mixing the spinning solution at temperatures much below room temperature does not adequately permit the formation of a homogenous mixture of acetone and cellulose acetate whereas temperatures above the boiling point of acetone in the solution are clearly undesirable.
The solids content of the spinning solution is generally between 24 and 32 weight percent cellulose acetate with zero to very minor amounts of titanium dioxide. The cellulose acetate content is preferably above 25 up to 32 weight percent, more preferably about 26 to 30 weight percent. At the higher solids content, there is less acetone present in the spinning solution, thus the need for acetone recovery is reduced. However, at a solids content much above 32 weight percent, the spinning solution is too viscous to be extruded through the small spinnerette holes.
Whereas, at a solids content much below 25 weight percent, the flow rate of the dope through the spinnerette is difficult to control and the amount of acetone to recover is too high. Additionally, spinning solutions containing low solids when spun into fibers tend to cause the fibers to stick to the outside surface of the metal face of the spinnerettes and are, therefore, difficult to pull the filaments into a yarn.
The cellulose acetate used in the spinning solution has a falling ball viscosity that is preferably below 42 seconds, more preferably below 35 seconds. Falling ball viscosity is defined as the time in seconds for a stainless steel ball ~f 1/8 inch in diameter (3.17 mm) to pass between two sets of parallel and horizontal lines separated by 2.25 inches (5.71 cm) through a solution of 20 weight percent cellulose acetate and 80 weight percent acetone at 25C. Falling ball viscosity is generally reduced by lowering the average molecular weight of cellulose acetate. The molecular weight of cellulose acetate may be adjusted by proper selection of esterification conditions by those skilled in the art. The falling ball viscosity for this cellulose acetate is the preferred range of 20 to 42 seconds with a range of 25 to 40 seconds being more preferred. Cellulose acetates of falling ball viscosities higher than 42 seconds are less desirable since the resulting spinning solution becomes too viscous to ad?quately extrude through the fine diameter holes in the spinnerettes. However, a cellulose acetate that has a falling ball viscosity much below 15 seconds, when formed into a spinning solution, results in a spinning solution of too low a viscosity to permit fiber formation out of the end of the holes in the spinnerettes. The inherent viscosity of the cellulose acetate in the spinning solution is preferably 1.35 to 1.60 more preferably 1.45 to 1.58 with a cellulose acetate inherent viscosity below 1.56 being most preferred.
The spinning solution according to the present invention generally has minor amounts of titanium dioxide added and minor amounts of water. The amount of Ti02 in the total spinning solution is generally below one weight percent, more preferably below 0.5 weight percent, with a weight percent of Ti02 less than 0.3 weight percent being most preferred. A minor amount of Ti02 is added to increase the whiteness of the resulting filter tow whereas higher amounts of Ti02 tend to plug the fine spinnerette holes.
The amount of water present in the spinning solution of the present invention is generally less than 3 weight percent, more preferably between 1 and 2 weight percent. Amounts of water much above 3 weight percent tend to slow the drying time of the resulting fibers whereas amounts of water much below 1 weight percent are difficult to obtain since the acetone is recycled from water by distillation and ambient air is humid.
The spinning solution is spun according to the present invention at an elevated temperature through the holes in the spinnerettes that have a diameter of less than 36 ~m to form a fiber. The spinning temperature of the spinning solution in the process of the present invention is preferably as hot as possible but below the boiling point of acetone. The elevated temperature of the spinning solution is maintained by passing through a heated candlefilter. The candlefilter temperature is maintained by passing hot water through the internal channels of the candlefilter. The actual temperature of the spinning solution is a few degrees below the candlefilter water temperature. This hot water temperature is preferably between 40 and 65C with a temperature of 50 to 60C
being more preferred. Candlefilter water temperatures much above 65C can heat the spinning solution above the boiling point of the acetone and tend to cause the formation of bubbles on the surface of the extruded fibers. However, candlefilter water temperatures much below 40C causes the viscosity of the spinning solution to be too high and also lengthens the curing or drying time of the spun fiber.
The holes in the spinnerettes used in the process of the present invention can be of any shape.
However, these holes are preferably round due to the ease in manufacturing of round holes in spinnerettes.
Additionally fibers produced by extrusion through non-round holes tend to have an increased pressure drop when used in a tobacco smoke filter. This increased pressure drop is such that the same unit pressure drop for a fiber from a round spinnerette hole produces higher filtration efficiency than that of the fibers from a non-round spinnerette hole cross section, such as a Y cross section.
The diameter of the holes in the spinnerettes used in the process of the present invention are preferably between 20 and 36 Vim. In general, smaller hole sizes are required to spin fibers having lower average denier per filament. When producing cellulose acetate fibers having an average denier per filament of 1.2 (0.13 TEX), the diameter of the holes in the spinnerettes is more preferably 28 to 34 ~m with a diameter of 30 to 32 ~m being most preferred.
The spinnerettes of the present invention preferably have a round hole profile such that the conical section in the back of the hole gradually tapers to form a cylindrical hole at the exit of the spinnerette. The round hole profiles are more preferably selected from hyperbola and multi-angle hole profiles. The surfaces of the spinnerette holes are preferably extremely smooth. These spinnerette holes more preferably have a surface roughness less than 0.05 Ra Vim. Ra indicates the arithmetic roughness average of the surface.
g _ The spinnerettes of the present invention are preferably of improved quality compared to the quality of spinnerettes acceptable for producing fibers of cellulose acetate having filament size in the range of 2 to 8 denier per filament (0.22 to 0.89 TES). This improved quality is especially manifest in the uniform and symmetrical shape of holes having extremely smooth surface finish. The holes at the exit of the spinnerette have cylindrical shape of 30 ~m in diameter and lengths which may be selected within the range of 0.5 to 1.5 times the diameter of the hole.
The improved quality spinnerette holes preferably have cylindrical sections with a surface roughness of 0.005 to 0.025 Ra Vim. The upstream portion of the spinnerette holes is commonly known as the countersink and has a profile which gradually increases for the diameter of the cylindrical hole section by gradually increasing the angle that the wall of the countersink makes with the axis of the hole. This may be accomplished by having a continuously increasing angle of the countersink wall with a profile such as that of a parabola. Alternatively, the countersink may be comprised of multiple frustoconical sections in which the apex angles of the sections increase as the diameter of frustoconical profile increases. For example, for two frustoconical sections, the smallest frustoconical section adjacent to and immediately upstream from the cylindrical section may have an apex angle in the range of 10 to 30 degrees and the length 34 of said section may be 3 to 10 times the diameter of the cylindrical section of the spinnerette hole. For the frustoconical section next farther upstream, the apex angle of said section may be in the range of 40 to 70 degrees and the length may be greater than 10 times the diameter of the cylindrical section of the spinnerette hole. The frustoconical sections of improved quality spinnerette holes preferably have a surface roughness within the range of 0.025 to 0.050 Ra Vim. The exterior surface or face of the improved quality spinnerette preferably has a surface roughness $ Of 0.005 t0 0.025 Ra ~,l.m.
By contrast, spinnerettes that are acceptable for producing cellulose acetate fibers having a denier per filament in the range of 2 to 8 (0.22 to 0.89 TEX) when a single countersink of frustoconical section can have a apex angle of 40 to 70 degrees. The smoothness of the finish of surfaces of the cylindrical holes, the frustoconical section and the exterior face of these spinnerettes is not as important as that of spinnerettes employed for producing fiber having less than 1 . 4 denier per f filament ( 0 . 16 TEX) .
The fiber that is spun through the spinnerette holes is dried or cured in a gaseous media at a temperature of 50 to 80C. This drying is preferably conducted in a drying cabinet with a lower top air temperature and a higher bottom air temperature of 60 to 110C. These temperatures are more preferably 60 to 70C for the top and 70 to l00C for the bottom with a bottom cabinet temperature of 80 to 90C being most preferred.
The spun fibers, prior to complete curing or drying, are spun at a draw ratio (winding speed/extrusion speed) of 0.9 to 1.7, more preferably 1 to 1.6 with a draw ratio of 1.2 to 1.5 being most preferred. At draw ratios much below 0.9 the fibers tend to flutter together and stick since the shrinking fiber does not make up for the reduced take up speed.
V~Ihereas draw ratios much above 1.7 cause fiber breakage due to the significant stretching of fibers.
It is preferred that the draw ratio generally be higher than 1 to help lower the denier, thus a draw ratio of 1.2 to 1.5 is most preferred.
The ultra-fine denier cellulose acetate fibers provided according to the present invention generally have an average denier per filament of less than 1.4 (0.16 TEX) more preferably less than 1.2 (0.13 TEX).
The fibers produced according to the present invention generally have an average denier per filament range of 0.6 to 1.4 (0.07 to 0.16 TEX) more preferably 1.0 to 1.4 (0.11 to 0.16 TEX) with an average denier per filament of 1.0 to 1.2 (0.l1 to 0.l3 TEX) being most preferred. Average denier per filaments of greater than 1.4 (0.16 TEX) do not adequately increase the filtration efficiency of filter products to be of great benefit. Whereas, an average denier per filament much below 1.0 (0.11 TEX) does not significantly increase filtration efficiency to match the increased pressure drop across a filter.
The following examples are to illustrate the present invention but should not be intended to limit the reasonable scope thereof.
EXAMPLES
EXAMPLE I
A spinning solution was formed by mixing at a temperature of 35~C 26.4 wt. percent cellulose acetate, 0.133 wt. percent titanium dioxide, less than 2 wt. percent water and the remainder being the solvent, acetone. The cellulose acetate had a falling ball viscosity of 40 seconds and an acetyl content of 39.5 wt. percent. This spinning solution was filtered and was spun through 30 and 32 ~.m round-hole dry spinnerettes from Nippon Nozzle Ltd., there being 450 holes in each spinnerette, and the holes being of improved surface finish with multiple-conical taper leading to the final cylindrical holes as described above. A total denier of 515 and 520 (57 and 58 TEX) were obtained at the speed of 466 m/m and 453 m/m, respectively. The spinning draws were 1.54 and 1.35 and denier per filaments were 1.14 and l.16 (0.13 and 0.13 TEX) for these respective runs. The candlefilter water temperature was set at 55~C, top air temperature was set at 75~C, and bottom air temperature was set at 90~C for both spinning runs. Spinning performance was satisfactory and yarn quality was satisfactory at these speeds. At these spinning conditions, a few yarn packages were successfully spun. The spinning performance of the 32 ~.m diameter hole spinnerette was better than that of the 30 ~m diameter hole spinnerette.
EXAMPLE II
A spinning solution was formed as described in Example I. This spinning solution was filtered and spun through a spinnerette having 450 round holes of 32m diameter and improved hole quality as described in Example I. The 450-filament strand had a total denier of 532 (59 TEX), an average of 1.20 denier per filament (0.13 TEX) and a calculated spin draw of 1.52. The spinning speed was 525 m/m, and other spinning conditions were like those described in Example I. One hundred and sixteen package strands of fiber were wound. Filter tows were made by combining 56 package strands to make a crimped tow of 30,000 total denier. These tows were processed into filter rods on a miniature/PM-2 plugmaker machine. Pressure drop generation of filter rods was measured on a Filtrona APD 2-V machine. Filters with 23.95 mm circumferences and 3l.5 mm length were cut from the rods, and they were attached to commercial cigarette tobacco columns. These cigarettes with 1.2 denier per filament (0.13 TEX) tow filters were tested for filtration efficiency by the FTC method. These results are shown in Table 1.
Table 1 Tow Item Rod Dimension Rod P.D. Rod Wt, 1.2/30,000/Reg. 24.45mm Cir. x 126mm L. 490mm 58omg 1.2/30,000/Reg. 24.45mm Cir. x 126mm L. 685mm 660mg 3.0/35,000/Y 24.45mm Cir. x 126mm L. 280mm*
ssomg 3.0/35,000/Y 24.45mm Cir. x 126mm L. 3'.'9mm*
660mg Filter Dimension Filter P.D. Tar Fil. Eff.
1$ 24.45mm x31.5mm L. 122.5mm 65.80 24.45mm x31.5mm L. 171.5mm 74.5%
24.45mm x31.5mm L. 122.5mm 58.0%
24.45mm x31.5mm L. 171.5mm 64.4%
* Theoretical values based on mathematical models.
As shown in this example, the pressure drop generation and filtration efficiencies of 1.2 denier (0.13 TEX) regular round cross section filter tow are significantly higher than 3.0 denier (0.33 TEX) Y cross section filter tow which is more commonly used in cigarette filters.
EXAMPLE III
A portion of the spinning solution prepared in Example II was used to spin fiber through spinnerettes having round holes of 32 ~m diameter and having normal surface finish and the single-conical taper leading to the final cylindrical holes at the exits of the spinnerette face. Fiber was able to be produced, however the frequency of breaks indicate that satisfactory commercial spinning could not be achieved at any of several spinning conditions of winding speed in the range of 400 to 600 m/m and of candle-filter water temperatures in the range of 50 to 65~C.
EXAMPLE IV
A spinning solution was formed by mixing at a temperature of 35~C 27.1 wt. percent cellulose acetate, 0.133 wt. percent titanium dioxide, less than 2 wt. percent water the remainder being the solvent, acetone. The cellulose acetate had a falling ball viscosity of 37 seconds and an acetyl content of 39.5 wt. percent. This spinning solution was filtered and was spun through a 32 ~,m round-hole spinnerette, there being 450 holes in the spinnerette and the holes being of improved surface finish with multiple-conical taper leading to the final cylindrical holes as described in Example I. A total denier of 539 was obtained at the speed of 710 m/m. The calculated spinning draw was 1.56 and the average denier per filament was 1.20 (0.13 TEX). The candle-filter water temperature was set at 60~C, the top air temperature was set at 70~C, and the bottom air temperature was set at 90~C. Even with this relatively high level of cellulose acetate concentration in the spinning solution and relatively high spinning speed, the spinning performance was satisfactory and 90 packages of fiber with each having 3.4 pounds of fiber were spun. A
bundle of 56 package strands were crimped into a tow on a crimper. Satisfactory crimped tows were made and these tows were processed into filter rods on a miniature/PM-2 plugmaker without any difficulty. Pressure drop of filter rods was measured on a Filtrona APD 2-V machine, and filtration efficiencies of 15 mm filters were measured by the FTC method. Cigarettes were smoked on the smoking machine up to 23 mm from the mouth end of the cigarette to measure the filtration efficiencies. The pressure drop measurement and filtration efficiencies results are shown in Table 2.
Table 2 Tow Item Rod Dimension Rod P.D. Rod Wt.
1.2/30,000/Reg. 23.95mm Cir. x 120mm L. 622mm 640mg 1.2/30,000/Reg. 23.95mm Cir. x 120mm L. 800mm 877mg 3.0/35,000/Y 23.95mm Cir. x 120mm L. 423mm 640mg 3.0/35,000/Y 23.95mm Cir. x 120mm L. - 877mg**
Filter Dimension Filter P.D. Tar Fil. Eff.
23.95mm xl5mm L. 78mm 45.2g 23.95mm xl5mm L. 114mm 52.5%
23.95mm xl5mm L. 78mm 42.0%
23.95mm xl5mm L. 114mm 45.9g*
* Theoretical values based on mathematical models.
** Not achievable weight for the size of rod.
As shown in Table 2, significant increases of pressure drop generation and filtration efficiencies were observed when compared with a conventional filter material.
EXAMPLE V
A spinning trial was performed to optimize the spinning condition for making ultra-fine denier filaments. A
fractional factorial experiment was performed with 6 spinning variables such as denier per filament, candlefilter water temperature, cabinet top air temperature and flow rate, and cabinet bottom air temperature and flow rate. In this experiment, a regular spinning solution which had 26.4 weight percent cellulose acetate, 0.113 weight percent Ti02, less than 2 wt. percent water and the remainder being the solvent, acetone, was used. At each spinning condition, maximum spinning speed was measured by increasing the godet roll speed gradually until the bundle of filaments started to generate broken filament. The maximum spinning speeds obtained were fitted to a regression model as follows:
Maximum Spinning Speed = 476.2 + 102.9 x DPF - 14.9 x Top Air Temp.
+ 2.1 x Candlefilter Temp.
- 5.4 x Top Air Temp. x Candlefilter Temp.
The coefficient of correlation (R2) was 0.995. This regression model showed that the lower denier per filament is more difficult to spin, and low top air temperature is preferred to spinning low denier per filament cellulose acetate fiber.
The spinning trials in the examples proved that ultra-fine denier acetate fiber can be spun without reducing the solids level of the spinning solution. For spinning ultra-fine denier fiber, it is essential to reduce the cellulose acetate I.V, or falling ball viscosity low enough to make a spinning solution with a viscosity below the level obtained by reduced solids spinning solution. Our spinning trials were confined to 1.2 denier per filament fiber (0.13 TEX), but it is possible to spin lower than 1.2 denier without changing the dope solids, if the acetate I.V. is lowered below 1.56 but not lower than l.35. An acetate I.V. lower than 1.35 would make yarn tensile property unacceptably low.
Claims (16)
1. A process for the production of ultra-fine denier cellulose acetate fibers comprising:
(A) forming a spinning solution containing above 25 up to 32 weight percent cellulose acetate, less than one percent TiO2, less than 3 percent water with the remainder being acetone, wherein said cellulose acetate has a falling ball viscosity of 15 to 70 seconds;
(B) spinning said spinning solution at an elevated temperature through spinnerettes having a multiplicity of holes having a diameter less than 36 microns to form fibers;
(C) drying said fibers in a gaseous media that is at an initial temperature of 50 to 80° C wherein said fibers are spun at a draw ratio of 0.9 to 1.7 thereby producing fibers having an average denier per filament of less than 1.4.
(A) forming a spinning solution containing above 25 up to 32 weight percent cellulose acetate, less than one percent TiO2, less than 3 percent water with the remainder being acetone, wherein said cellulose acetate has a falling ball viscosity of 15 to 70 seconds;
(B) spinning said spinning solution at an elevated temperature through spinnerettes having a multiplicity of holes having a diameter less than 36 microns to form fibers;
(C) drying said fibers in a gaseous media that is at an initial temperature of 50 to 80° C wherein said fibers are spun at a draw ratio of 0.9 to 1.7 thereby producing fibers having an average denier per filament of less than 1.4.
2. The process according to Claim 1 wherein the spinning solution contains above 25 up to 32 weight percent cellulose acetate, 0 up to 1 weight percent TiO2, up to 3 weight percent water, and 64 to 76 weight percent acetone, wherein said cellulose acetate has a falling ball viscosity of less than 42 seconds.
3. The process according to Claim 2 wherein said cellulose acetate has a falling ball viscosity of no more than 35 seconds.
4. The process according to Claim 1 wherein the spinning solution contains 26 to 30 weight percent cellulose acetate.
5. The process according to Claim 1 wherein said spinning is conducted at an elevated temperature below the boiling point of acetone through spinnerettes having a multiplicity of round holes having a diameter of 20 to less than 36 µm.
6. The process according to Claim 5 wherein the holes of said spinnerettes have a diameter between 28 and 34 µm.
7. The process according to Claim 1 wherein said spinnerettes have a round hole profile such that the conical section in the back of the hole gradually tapers to form a cylindrical hole at the exit of the spinerette.
8. The process according to Claim 7 wherein said round hole profiles are selected from the group consisting of hyperbola and multi-angle hole profiles.
9. The process according to Claim 1 wherein the surface of the spinnerette holes are extremely smooth having a surface roughness less than 0.05 Ra µm.
10. The process according to Claim 9 wherein said spinnerette holes have a surface roughness of 0.01 to 0.05 R a µm.
11. The process according to Claim 1 wherein said gaseous media is air and said fibers are dried in a cabinet that has a lower top air temperature and a higher bottom air temperature of 60 to 110°C.
12. The process according to Claim 11 wherein said drying is conducted in a spinning cabinet with a top air temperature of 60 to 70°C
and a bottom air temperature of 70 to 100°C.
and a bottom air temperature of 70 to 100°C.
13. The process according to Claim 1 wherein said draw ratio is 1.2 to 1.5.
14. The process according to Claim 1 wherein said fibers have an average TEX of 0.07 to 0.16.
15. The process according to Claim 14 wherein said fibers have an average TEX of 0.11 to 0.14.
16. The process according to claim 1 wherein said spinning solution at an elevated temperature in (b) is maintained at this temperature by passing through a heated candle filter that is heated by hot water at a temperature of about 40 to 65°C.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/943,824 | 1992-09-14 | ||
| US07/943,824 US5269996A (en) | 1992-09-14 | 1992-09-14 | Process for the production of fine denier cellulose acetate fibers |
| PCT/US1993/008357 WO1994006954A1 (en) | 1992-09-14 | 1993-09-07 | Process for the production of fine denier cellulose acetate fibers |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2143092A1 CA2143092A1 (en) | 1994-03-31 |
| CA2143092C true CA2143092C (en) | 1999-07-27 |
Family
ID=25480330
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002143092A Expired - Fee Related CA2143092C (en) | 1992-09-14 | 1993-09-07 | Process for the production of fine denier cellulose acetate fibers |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US5269996A (en) |
| EP (1) | EP0660888B1 (en) |
| JP (1) | JP3200068B2 (en) |
| CN (1) | CN1048764C (en) |
| AT (1) | ATE146532T1 (en) |
| BR (1) | BR9307045A (en) |
| CA (1) | CA2143092C (en) |
| DE (1) | DE69306801T2 (en) |
| WO (1) | WO1994006954A1 (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4302055C1 (en) * | 1993-01-26 | 1994-03-24 | Rhodia Ag Rhone Poulenc | Cellulose acetate filaments prepd. by spinning from an acetone soln. - are useful for the prodn. of cigarette filter tow |
| DE19730485C2 (en) * | 1997-07-16 | 2003-07-03 | Rhodia Acetow Ag | Trilobal cross-section cellulose acetate filaments |
| MY138902A (en) * | 2000-04-20 | 2009-08-28 | Philip Morris Prod | "cigarette filters of shaped micro cavity fibers impregnated with flavorant materials" |
| MY128157A (en) | 2000-04-20 | 2007-01-31 | Philip Morris Prod | High efficiency cigarette filters having shaped micro cavity fibers impregnated with adsorbent or absorbent materials |
| US6695992B2 (en) * | 2002-01-22 | 2004-02-24 | The University Of Akron | Process and apparatus for the production of nanofibers |
| US7585441B2 (en) * | 2004-06-25 | 2009-09-08 | Celanese Acetate, Llc | Process of making cellulose acetate tow |
| KR101074970B1 (en) | 2008-09-30 | 2011-10-18 | 미쓰비시 레이온 가부시끼가이샤 | Method of producing acetate fiber bundle and acetate fiber bundle produced thereby |
| CN103060939B (en) * | 2012-12-24 | 2014-09-03 | 四川大学 | Preparation method of cellulose acetate fiber through polybasic carboxylic acid crosslinking |
| CN103806116B (en) * | 2014-02-20 | 2014-12-10 | 胡宏伟 | Viscose staple fiber spinning after-treatment method |
| CN104195652B (en) * | 2014-08-21 | 2016-05-18 | 济南大自然新材料有限公司 | Acetate fiber production line |
| JP6580348B2 (en) * | 2015-03-04 | 2019-09-25 | 株式会社ダイセル | Cellulose acetate fiber, production method thereof, and filter tow for tobacco |
| JP7154808B2 (en) * | 2018-04-20 | 2022-10-18 | 株式会社ダイセル | Spinning device and spinning method |
| CN110356063A (en) * | 2019-08-15 | 2019-10-22 | 苏州盈知翔纺织有限公司 | A kind of biomass regenerated fiber fabric |
| CN110578180B (en) * | 2019-09-27 | 2021-09-17 | 武汉轻工大学 | Acidified modified cellulose fiber, preparation method thereof and application thereof in processing edible oil |
| CN114775128B (en) * | 2022-05-12 | 2023-06-23 | 山东联润新材料科技有限公司 | Spinning process of acetate fiber functional blended yarn |
| WO2024229062A1 (en) * | 2023-05-04 | 2024-11-07 | Eastman Chemical Company | Sectional and combined cellulosic yarn packages and methods of production and processing thereof |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3068063A (en) * | 1962-12-11 | Cellulose acetate spinning solutions | ||
| BE562946A (en) * | 1953-12-28 | |||
| US3382305A (en) * | 1954-10-29 | 1968-05-07 | Du Pont | Process for preparing oriented microfibers |
| US2838364A (en) * | 1955-01-07 | 1958-06-10 | Eastman Kodak Co | Dry spinning process |
| US3038780A (en) * | 1959-10-23 | 1962-06-12 | Eastman Kodak Co | Spinning solution containing an aluminum complex |
| US3033698A (en) * | 1959-10-23 | 1962-05-08 | Eastman Kodak Co | Cellulose acetate spinning solutions and process of spinning fine denier filaments |
| US3080611A (en) * | 1960-11-08 | 1963-03-12 | Eastman Kodak Co | Method for the production of cigarette filters |
| US3608041A (en) * | 1964-01-09 | 1971-09-21 | Celanese Corp | Spinning process |
| JPS57117614A (en) * | 1980-07-25 | 1982-07-22 | Mitsubishi Rayon Co Ltd | Preparation of cellulose acetate fibrous aggreagate |
| US5240665A (en) * | 1991-12-31 | 1993-08-31 | Eastman Kodak Company | Process of making cellulose acetate fibers from spinning solutions containing metal oxide precursor |
-
1992
- 1992-09-14 US US07/943,824 patent/US5269996A/en not_active Expired - Fee Related
-
1993
- 1993-09-07 AT AT93921367T patent/ATE146532T1/en not_active IP Right Cessation
- 1993-09-07 BR BR9307045-4A patent/BR9307045A/en not_active Application Discontinuation
- 1993-09-07 EP EP93921367A patent/EP0660888B1/en not_active Revoked
- 1993-09-07 DE DE69306801T patent/DE69306801T2/en not_active Revoked
- 1993-09-07 JP JP50665194A patent/JP3200068B2/en not_active Ceased
- 1993-09-07 WO PCT/US1993/008357 patent/WO1994006954A1/en not_active Application Discontinuation
- 1993-09-07 CA CA002143092A patent/CA2143092C/en not_active Expired - Fee Related
- 1993-09-14 CN CN93116812A patent/CN1048764C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0660888A1 (en) | 1995-07-05 |
| JP3200068B2 (en) | 2001-08-20 |
| DE69306801D1 (en) | 1997-01-30 |
| EP0660888B1 (en) | 1996-12-18 |
| DE69306801T2 (en) | 1997-04-10 |
| CN1048764C (en) | 2000-01-26 |
| US5269996A (en) | 1993-12-14 |
| BR9307045A (en) | 1999-10-13 |
| ATE146532T1 (en) | 1997-01-15 |
| WO1994006954A1 (en) | 1994-03-31 |
| JPH08501606A (en) | 1996-02-20 |
| CA2143092A1 (en) | 1994-03-31 |
| CN1088637A (en) | 1994-06-29 |
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